Phage group II staphylococcal strains with chromosomal and extrachromosomal genes for exfoliative toxin production

Abstract

Staphylococcal phage group 2 strain UT0007 was previously shown to contain a high-molecular-weight plasmid containing genes for exfoliative toxin (ET) and bacteriocin production. Phage group 2 strains UT0002 and UT0003 (Tox+Bac-) underwent a twofold and ninefold loss of ET activity, respectively, after growth at 44 C for 18 h. Strain UT0002 also lost total bacteriocin activity. Both strains contained (i) a 56S plasmid that was lost from those substrains showing reduced ET activity and (ii) a 21S plasmid with a gene for cadmium resistance that could be transduced into two recipient strains. Since the ET plasmid-negative substrains still made ET, it was postulated that this residual toxin was made from chromosomal genes. In characterizing the plasmid species from strains UT0002 and UT0003, the 21S but little or no 56S plasmid deoxyribonucleic acid could be isolated after centrifugation of cleared lysates from these strains on dye-buoyant density gradients. Treatment of cleared lysates from strain UT0002 with ethidium bromide, Pronase, or sodium dodecyl sulfate, but not heat at 60 C, induced conversion of the 56S closed circular ET plasmid to a 38S open circular form as determined after centrifugation on 5 to 20% neutral sucrose gradients.

Plasmids in Epidermolytic Strains of Staphylococcus aureus

“…Rogolsky and his co-workers in a series of studies have attempted to define the genetic basis of ET production in S. aureus (Rogolsky et al, , 1976Warren et al, 1974Warren et al, , 1975Wiley 8z Rogolsky, 1977). In early studies no evidence was obtained for linkage of ET determinants to lysogenic phages.…”

“…In early studies no evidence was obtained for linkage of ET determinants to lysogenic phages. The capacity to produce ET was either completely or partly lost by some strains when they were grown at high temperatures or in the presence of ethidium bromide, which suggested that a plasmid might be implicated in the expression of the toxin (Rogolsky et al, , 1976. Many toxin-producing strains also produced a bacteriocin .…”

“…In some toxin-producing strains the capacity to form ET could not be completely eliminated (Rogolsky et al, , 1976. This partial curing was correlated with the loss of the 56s plasmid which suggested that in some strains both plasmid and chromosomal determinants might be involved in ET synthesis (Rogolsky et al, 1976). Evidence has been presented that the chromosomally specified ET was antigenically distinct from that which was plasmid-determined (Wiley & Rogolsky,19 7 7).…”

Cloning of the gene coding for staphylococcal exfoliative toxin A and its expression in Escherichia coli

“…(ii) ETA protein is heterogenous in its isoelectric point, while ETB is homogenous [2]. (iii) ETA protein is coded by a chromosomal gene, but ETB is known to be coded for by a plasmid gene [7][8][9][10]. These toxins have other biological properties, such as a strict animal species specificity, age dependence, organ or tissue tropism as well as their curious immunogenicity [11].…”

Epidermolytic toxin serotype B ofStaphylococcus aureusis plasmid-encoded

“…Two serotypes of epidermolytic toxin (ET) are specified by strains of S. aureus which cause the scalded skin syndrome [1]. Genetic studies have suggested that the gene coding for serotype A ET (eta) is chromosomal while expression of ET serotype B is plasmid-controlled [2,3]. However, these studies did not show conclusively that the etb structural gene was actually located on the plasmid because of difficulties in transferring it to non-toxigenic strains.…”